In recent years semiconductor devices have become smaller and smaller in order to increase the number of semiconductor devices on each wafer and in order to form more complex semiconductor devices. In order to make smaller semiconductor devices, new materials and processing techniques are continually being developed. One new processing material which is desirable for use in semiconductor manufacturing processes is aerogel films.
At present, aerogel films are difficult to manufacture and are expensive to manufacture. One of the primary reasons that the manufacture of aerogel films is difficult and expensive is the requirement that the aerogel film be cured under super critical conditions. These super critical conditions include high temperature and high-pressure requirements. Typically, a temperature of over 100 degrees centigrade and a pressure of over 1500 pounds per square inch is required for curing an aerogel film.
In a typical prior art process for curing an aerogel film, one or more semiconductor wafers are placed into an autoclave immediately after the application of the aerogel film to the semiconductor wafer. The process of sealing the autoclave is time consuming. In addition, the heating process is inefficient and takes a relatively long time because the entire pressure vessel of the autoclave must be heated. Moreover, the process of unsealing the autoclave is also time consuming. This makes the use of aerogel films impractical for use in modern high speed manufacturing processes.
A typical prior art autoclave is shown in FIG. 1a. Autoclave 1 is shown to include pressure vessel 3 which is disposed within frame 2. Heating system 4 is shown to surround the exterior of pressure vessel 3. Tubing 6 allows for gas to be pumped into, and removed from pressure vessel 3. In one prior art method for curing an aerogel film, an inert gas such as nitrogen is used as a medium. Door 5 fits over the top of pressure vessel 3 so as to enclose pressure vessel 3. Nuts 9 are screwed over bolts 7 so as to hold door 5 tightly against pressure vessel 3. Semiconductor wafers 10 are shown to be disposed on cassette tray 11 which is placed within pressure vessel 3.
With reference now to prior art FIG. 1b, a bottom view of top 5 is shown including openings 8. In operation, pressure vessel 3 is enclosed by placing top 5 of prior art FIG. 2 such that openings 8 fit over bolts 7 of FIG. 1. Next, each nut 9 of FIG. 1a must be placed over one of bolts 7 and each individual nut 9 must be separately tightened. Due to the high-pressure that is to be applied to pressure vessel 3, each nut 9 must be carefully tightened using a wrench. This is a time-consuming process. Unless each nut is sufficiently tightened, a leak will result which will prevent full pressurization.
Next, referring again to FIG. 1a, an inert gas is pumped through one of tubes 6 to us to apply a pressure of 1,500 pounds per square inch within pressure vessel 3. Heating system 4 is activated such that heat is applied to pressure vessel 3. Heating system 4 heats pressure vessel 3. The heat moves through the walls of pressure vessel 3 so as to heat the inside of pressure vessel 3, thereby heating semiconductor wafers 10.
After the curing process is complete, the pressure is released through one of tubes 6 and heating system 4 is deactivated. In order to remove the semiconductor wafers from pressure vessel 3, each of nuts 9 must first be removed using a wrench. Then, door 5 is removed which then allows the semiconductor wafers to be removed from pressure vessel 3. This is a time-consuming process. Thus, this process is unsuitable for use in conjunction with current mass production methods for producing semiconductor devices. In addition, this type of autoclave is inefficient due to the fact that the heating system 4 must heat pressure vessel 3 in order to heat the interior of pressure vessel 3.
What is needed in is an autoclave which will allow for the mass production of semiconductor devices. More particularly, an autoclave is needed which can be easily sealed and unsealed and which can provide for increased throughput. In addition, an autoclave is needed which can efficiently and quickly heat semiconductor wafers. The present invention meets the above needs.